Hydrocephalus is a condition in which there is a lack of absorption, blockage of flow, or overproduction of the cerebral spinal fluid (CSF) that is found inside the ventricles (fluid-filled areas) of the brain. This may result in a build up of fluid that can cause the pressure inside of the head to increase and the skull bones to expand to a larger-than-normal appearance.
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Hydrocephalus occurs in approximately one out of 500 births. The following are the primary reasons why hydrocephalus occurs:
- blockage of the CSF flow inside of the head
- problems with the body absorbing the CSF
- overproduction of the CSF
Hydrocephalus can occur either as a condition present at birth (congenital), or it can be acquired later in life. When hydrocephalus is not related to a known genetic cause, it is thought that many factors, both genetic and environmental, contribute to the condition. In a small percentage of babies, a single gene defect on the X chromosome, or another chromosome, is responsible for the condition. In these cases, the chance for recurrence is higher. Once a child has been born with hydrocephalus that is not known to be caused by a single gene defect, the chance for it to happen again in another child is 1 to 5 percent.
Causes of acquired hydrocephalus may include the following:
- bleeding inside the head
- birth injury
- abnormal blood vessel formation inside of the head
The following are the most common symptoms of hydrocephalus in babies. However, each baby may experience symptoms differently. Symptoms may include the following:
- a full or bulging fontanel (soft spot located on the top of the head)
- increasing head circumference
- bulging eyes and an inability of the baby to look upward with the head facing forward
- very noticeable scalp veins
- increased irritability
- high-pitched cry
- poor feeding
- projectile vomiting
- sleepiness or less alert than usual
- developmental delays
The symptoms of hydrocephalus may resemble other conditions or medical problems. Always consult your baby's physician for a diagnosis.
Hydrocephalus may be diagnosed before birth by prenatal ultrasound, a diagnostic imaging technique which uses high-frequency sound waves and a computer to create images of blood vessels, tissues, and organs. Ultrasounds are used to view internal organs as they function, and to assess blood flow through various vessels. In many cases, hydrocephalus does not develop until the third trimester of the pregnancy and, therefore, may not be seen on ultrasounds performed earlier in pregnancy.
The diagnosis of congenital hydrocephalus may be made at birth and after diagnostic testing. During the examination, the physician obtains a complete prenatal and birth history of the baby. He/she may also ask if there is a family history of any hydrocephalus or other medical problems. The physician will also ask about developmental milestones in older babies since hydrocephalus can be associated with other neuromuscular disorders. Developmental delays may require further medical follow-up for underlying problems.
The baby's head may appear larger than normal. A measurement of the circumference of the baby's head is taken and compared to a scale that can identify normal and abnormal ranges.
Diagnostic tests that may be performed to confirm the diagnosis of hydrocephalus include:
- x-ray - a diagnostic test which uses invisible electromagnetic energy beams to produce images of internal tissues, bones, and organs onto film.
- magnetic resonance imaging (MRI) - a diagnostic procedure that uses a combination of large magnets, radiofrequencies, and a computer to produce detailed images of organs and structures within the body.
- computed tomography scan (Also called a CT or CAT scan.) - a diagnostic imaging procedure that uses a combination of x-rays and computer technology to produce cross-sectional images (often called slices), both horizontally and vertically, of the body. A CT scan shows detailed images of any part of the body, including the bones, muscles, fat, and organs. CT scans are more detailed than general x-rays.
Specific treatment for hydrocephalus will be determined by your baby's physician based on:
- your baby's gestational age, overall health, and medical history
- the extent of the condition
- the type or cause of condition
- your baby's tolerance for specific medications, procedures, or therapies
- expectations for the course of the condition
- your opinion or preference
The goal of treatment is to reduce the pressure in the baby's head and to properly drain the cerebral spinal fluid (CSF). Occasionally, medications or procedures to draw off the extra CSF may be used.
Surgery may be needed for some cases of hydrocephalus. Surgery usually involves placing a mechanical shunting device into the baby's head to help drain the extra CSF from the brain and redirect the extra fluid to another part of the body to be absorbed. A common type of shunt is the ventriculoperitoneal shunt.
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The shunt consists of three parts:
- a tube that is placed inside of the ventricular space
- a reservoir and valve to control the flow of CSF
- tubing that is directed under the skin to the abdomen, or less commonly to the heart or lung area
The shunt redirects the CSF out of the head through the tubing to a location elsewhere in the body where it can absorbed. The shunt is usually placed behind the ear and the tubing is threaded from behind the ear, under the skin to the area of the abdomen, heart, or lung. Your baby's physician will determine the drainage location based on your baby's condition, age, and other factors.
Potential complications from the shunts or surgery can include the following:
- shunt malfunction that results in under-drainage or over-drainage of the CSF
Other complications may include fever, vomiting , irritability, redness and swelling along the area of the tubing, or decreased alertness or lethargy.
These complications require prompt medical evaluation. Following surgery, you will receive instructions on how to care for your baby at home and information about signs or symptoms requiring medical care.
Hydrocephalus can affect the brain and a baby's development. The extent of the problem is dependent on the severity of the hydrocephalus, and the presence of brain or other organ system problems.
The key to treating hydrocephalus is early detection, treatment, and prevention of infection. A baby with hydrocephalus requires frequent medical evaluations to ensure proper shunt function. The medical team works hard with your family to provide education and guidance as your baby grows and develops.
Genetic counseling may be recommended by your baby's physician to discuss the risk of recurrence in future pregnancies, as well as prenatal testing for hydrocephalus.
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